JPH06347435A - Variety-fuel sensor - Google Patents

Abstract

PURPOSE: To provide a multi-fuel sensor high in reliability and low in cost using a resonant electromagnetic cavity resonating with frequency corresponding to a liquid mixture in order to measure the composition of at least two kinds of liquid fuel, and provide a multi-fuel feeder including the multi-fuel sensor and capable of controlling the operation of a vehicle according to the fuel mixture. CONSTITUTION: A first conductor 28 and a second conductor 30 provided in the first conductor 28 and short-circuited at one end to the first conductor 28 are concentrically combined, and a liquid-fuel mixture flows through a passage 32 formed between both conductors. A resonant electromagnetic cavity 64 with resonance frequency corresponding to this fuel mixture is formed, connected to an oscillator 72 and driven by the oscillator 72 so as to output a content signal indicating the fuel mixture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to multi-fuel systems, and more particularly to multi-fuel sensors that use resonant electromagnetic cavities to measure fuel composition.

[0002]

BACKGROUND OF THE INVENTION Interest in multi-fuel vehicles has increased dramatically in recent years. This is especially true for vehicles that operate on blends of gasoline and alcohol.

In this type of vehicle, it is necessary to monitor the fuel mixture ratio (for example, the weight percentage of alcohol) and adjust the engine performance. The signals from the multi-fuel sensor are communicated to and utilized by an electronic engine controller, which generally sets spark timing, exhaust gas recirculation and fuel enrichment appropriately. The multi-fuel system plays a particularly important role during open-loop feedback conditions such as cold start and large throttle opening.

Multi-fuel sensors are mainly divided into two types, optical and dielectric. Optical sensors utilize the refractive index or infrared absorption pattern of the fuel formulation. The dielectric sensor responds to changes in the dielectric constant of the fuel blend that are subject to changes in the fuel mix.

[0005]

SUMMARY OF THE INVENTION The present invention, in its primary aspect, is a multi-fuel sensor, ie, a sensor for measuring the fuel mixture ratio of at least two types of liquid fuel. The invention has particular applicability to gasoline / methanol blends.

The multi-fuel sensor has a pair of substantially coaxial conductors that are electrically shorted at one end. Two types of liquid fuel flow between these conductors. The sensor thereby establishes a resonant electromagnetic cavity through which the liquid fuel mixture flows, having an electrical resonance frequency corresponding to the fuel mixture. In connection with this scheme, a resonant electromagnetic cavity is coupled to and driven by the oscillator. A content signal indicative of the fuel mixture is responsively emitted.

It is therefore an object of the present invention to provide a multi-fuel supply system and sensor. Another object is to provide a multi-fuel supply that controls vehicle operation in response to fuel mix ratios monitored and measured in a resonant electromagnetic cavity. Yet another object is to provide a reliable, yet inexpensive multi-fuel sensor.

It is also an object of the present invention to provide a multi-fuel sensor that defines a resonant electromagnetic cavity that resonates at a frequency that depends on the fuel mixture. A further object is to provide a resonant electromagnetic cavity sensor that includes two substantially cylindrical and substantially coaxial conductors. Yet another object is a two-conductor resonant cavity sensor in which the vehicle fuel manifold acts as an outer conductor.

[0009]

These and other features, objects and advantages of the present invention are described or included in the description of some preferred embodiments which follow.

A preferred embodiment of the present invention will be described in detail with reference to the drawings.

1 to 4 using common reference numerals,
A preferred embodiment of the invention is shown. First, referring to FIGS. 1 and 2, the engine 14, the fuel tank 16,
The present invention is shown as a multifuel supply, generally designated 10, for a multifuel vehicle 12 having a fuel line 18 and an electric engine controller 20. As is well known, engine controller 20 adjusts certain parameters of engine performance based on the fuel mixture delivered through fuel line 18. In the preferred embodiment, a mixture of two liquid fuels, gasoline and alcohol (preferably methanol), is used, and the fuel mixture ratio is specified by the weight percentage of one liquid fuel.

The multi-fuel supply device 10 comprises a multi-fuel sensor 22, an oscillator device 24 and an output device 26. In the preferred embodiment, the sensor 22 includes a fuel line 1 for receiving at least a portion of the liquid fuel mixture.
Built in 8. The mixture flows through the sensor 22 towards the engine 14 (in the direction of the dotted arrow in FIG. 2).

With particular reference to FIG. 2, the multi-fuel sensor 22 comprises a first conductor 28 and a second conductor 30 positioned within the first conductor 28 in a generally coaxial arrangement. The first and second conductors 28, 30 are preferably
It is desirable that they are cylindrical and coaxial and that their lengths are almost the same. The liquid fuel mixture comprises first and second conductors 28,30.
Pass along the flow path 32 between.

The first conductor 28 includes first inlet and outlet ends 34 and 36, respectively. The second conductor 30 has second inlet and outlet ends 38, 40, respectively. The second inlet and outlet ends 38, 40 are sealed by inlet and outlet plugs 42, 44, respectively. The inlet plug 42 is generally flush with the second inlet end 38 and the plug 44 is inward from the second outlet end 40. The first and second conductors 28, 30 and the inlet and outlet plugs 42, 44 are preferably brass or stainless steel.

The coaxial arrangement between the first and second conductors 28, 30 is maintained by the inlet and outlet housings 46, 48, respectively. The inlet housing 46 includes an inlet fitting 50 adapted for sealing engagement with the fuel line 18 such that the inlet housing 46 receives liquid fuel.

The first inlet end 34 of the first conductor 18 is attached and sealed to the inlet housing 46 opposite the inlet fitting 50. The second conductor 30 is secured in place by a retaining plate or disc 52 having a central retaining opening 54 adapted to receive the second inlet end 38. In this preferred embodiment, the first conductor 2
8 to insulate the second conductor 30 from the holding disk 52.
Is non-conductive. The retaining disc 52 is further provided with a series of disc passages 56 that allow the flow of fuel from the inlet fitting 50 into the flow passage 32. Retaining disk 52 in a generally annular inner groove 58 in inlet housing 46.
Is fixed.

The outlet housing 48 includes an outlet fitting 60 to receive and retain the first outlet end 36 of the first conductor 28. Within the outlet housing 48, the first and second conductors 2
So that the inlet and outlet housings 46, 48 maintain coaxial alignment of the channels 8, 30 and the generally cylindrical channel 32,
The second outlet end 40 of the second conductor 30 is fixed in the substantially annular groove 62.

The outlet housing 48 is electrically conductive and includes first and second outlet ends 3 of the first and second conductors 28, 30.
6, 40 are electrically shorted, preferably to a ground conductor. A resonant electromagnetic cavity, generally designated 64, that resonates at a frequency depending on the fuel mixture or more specifically its dielectric constant, is thus set by the multi-fuel sensor 22.

The multi-fuel sensor 22 is further provided with drive and output terminals 66, 68 which are coupled to an oscillator device 24 and an output device 26, respectively. Drive and output terminals 66, 68 are provided substantially opposite the inlet housing 46 and extend through the inlet housing 46 for connection to the second conductor 30 or specifically the inlet plug 42. Inlet plug 4 via register 70
2 and the drive terminal 66 are connected.

In the preferred embodiment, the oscillator device 24
Is an oscillator 72 of fixed amplitude and fixed frequency. The preferred frequency range is 10 to 50 MHz. The oscillator 72 applies a drive voltage to the resonant cavity 64 of the multi-fuel cell 22 via the drive terminal 66 and the resistor 70. In response, a fuel mixing ratio or content signal proportional to the weight percentage of methanol in the fuel line 18 or proportional thereto is emitted. In the preferred embodiment, the output device 26 includes an output terminal 68.
Is a resistor 74 interconnecting the and the ground conductor, and the content signal is the voltage provided to the electronic engine controller 20.

Two advantages of the multi-fuel sensor 22 are simplicity of design and durability. These advantages reduce production and overall costs, which is a particularly important issue in the automotive industry. The sensor 22 further reduces the adverse effects of parasitic inductance and resistance, thereby increasing the accuracy of fuel mixture ratio measurements.

Here, FIG. 3 will be described. In the figure,
A second preferred embodiment of the invention is shown. Sensor 2
2 also includes a conventional peak detector 76 and a ramp generator 78 interconnected as shown. The frequency of the oscillator device 24 can be varied in a conventional manner, the oscillator frequency being approximately matched to the resonant frequency of the resonant electromagnetic cavity 64.

As the engine starts, the ramp generator 78 begins a frequency sweep, ie, a gradual increase in oscillator frequency, until the peak voltage from the outlet device 26 is detected by the peak detector 76. At that moment,
The voltage output of the ramp generator 78 is correlated with the resonant frequency of the cavity 64 to provide the content signal provided to the engine controller 20. The initiation of the frequency sweep at low frequencies (eg 10 MHz) largely avoids the detection of "pseudo" peaks due to resonant overtone modes.

The advantage of the preferred embodiment shown in FIG. 3 is that accuracy and significantly reduce the adverse effects on measurements due to impurities (eg water and salt) in the fuel formulation.
The resonant frequency of the resonant cavity 64 is slightly modified, even with the highest levels of impurities present in currently marketed fuels.

Here, FIG. 4 will be described. In the figure,
Another embodiment of the invention is shown. As is known in the art, the fuel line 18 is placed in close proximity to the engine 14.
Are coupled to the fuel manifold 80. Fuel manifold 80 is typically stainless steel and is thicker than fuel line 18. The fuel manifold 80 includes a series of ports 8 for distribution of fuel to fuel injectors (not shown).
Two are provided.

In the preferred embodiment, the fuel manifold 80 functions as the first conductor 28 of the multi-fuel sensor 22. Inlet and outlet housings 46, 48 interconnect the fuel lines 18 to the inlet and outlet ends of the fuel manifold 80, respectively. Inlet and outlet housing 4
The second conductor 30 held in position by 6, 48 is a solid brass rod 88. A series of non-conductive spacers 90 largely avoid vibration of the solid second conductor 30 and keep it insulated from the fuel manifold conductor 28.

The outlet end 86 of the fuel manifold 80 and the outlet segment 92 of the solid conductor rod 88 are shorted by the outlet housing 48, preferably to a ground conductor. The inlet segment 94 of the solid conductor rod 88 is fixed within the inlet housing 46 within the insulating support 96.

Various embodiments have been described herein. However, it should be understood that modifications and changes can be made without departing from the true scope and spirit of the invention as defined by the claims, which should be construed in view of the above description.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a multifuel vehicle incorporating a first preferred embodiment of the present invention.

2 is a partial cross-sectional view of the multi-fuel sensor of FIG.

FIG. 3 is a schematic diagram of a second preferred embodiment.

FIG. 4 is a side view of a fuel line and a rail showing a third preferred embodiment of the present invention.

[Explanation of symbols]

 22 Various Fuel Sensors 28 First Conductor 30 Second Conductor 32 Flow Path 64 Resonant Electromagnetic Cavity 72 Transmitter

Claims (1)

[Claims] 1. A multi-fuel sensor for measuring a fuel mixture ratio of at least two types of liquid fuel, wherein a first conductor and a second conductor in the first conductor and short-circuited to the second conductor are provided. A multi-fuel sensor including a liquid flow combination that defines a resonant electromagnetic cavity having a resonant frequency corresponding to the fuel mixture ratio.